Effect of Si Content on the Formation of {100} Orientation in 0.27% Al Non-oriented Electrical Steel during Cell-to-Dendrite Transition Process

The effects of Si content (0.73%, 2.23%, 4.57%) and solidification rate (10 µm/s, 35 µm/s, 80 µm/s) on the as-cast microstructure and crystal orientation of 0.27% Al non-oriented electrical steel have been studied by directional solidification technology. Si atoms were inclined to segregate on the trunks and stems of cells and dendrites, and precipitate in the form of quadrilateral Fe-Si particles with size less than 4 μm. Increasing Si content would lead to a decrease in thermal conductivity of steel and directly cause an increase in temperature gradient of liquid steel, and as a result, make solid–liquid interface more stable and easier to grow as cell crystal. Moreover, decreasing solidification rate could further aggravate Si segregation at solid–liquid interface. Higher Si content (4.57%) together with lower solidification rate (10 µm/s) was more beneficial to the grain nucleation with {100} orientation, whereas higher solidification rate (80 µm/s) played a major role in the grain nucleation with {110} orientation.